Heat exchange structure for a hot air heater

ABSTRACT

A heat exchange structure for an air heater furnace wherein the cross-over port structure from the first stage of a heat exchanger is an elongated rectangular inlet into the second stage of the heat exchanger, which has a number of spaced flanges therein for guiding the flow of the products of combustion more evenly in their passage to the outlet of the second stage.

United States Patent Tyson et al.

[451 May 16, 1972 HEAT EXCHANGE STRUCTURE FOR A HOT AIR HEATER Thomas L.Tyson; Edward G. Craze, Jr., both of Richmond, Va.

Assignee: Texaco Inc., New York, NY.

Filed: June 1, 1970 Appl. No.2 42,366

Inventors:

US. Cl. ..l26/9l R, 126/106, 126/110 R, 165/155 Int. Cl. ..F24c 3/00,F24h 3/06 FieldofSearch... ..126/90,91, 110, 1108, 116,

References Cited UNITED STATES PATENTS Parrish ..126/110 X 1,334,0393/1920 Lape ..126/116 2,263,098 11/1941 Muel1er.. ....126/110 3,151,67310/1964 Strache ....l26/116X FOREIGN PATENTS OR APPLICATIONS 875,9758/1961 Great Britain ..126/1 10 B Primary ExaminerCharles .1. MyhreAttorney-Thomas H. Whaley and Carl G. Rets [5 7] ABSTRACT A heatexchange structure for an air heater furnace wherein the cross-overportstructure, from the first stage of a heat exchanger is an elongatedrectangular inlet into the second stage of the heat exchanger, which hasa number of spaced flanges therein for guiding the flow of the productsof combustion more evenly in their passage to the outlet of the secondstage.

6 Claims, 8 Drawing Figures PATENTEUW 16 m2 SHEET 1 [IF 4 P'A'TENTEnnAY16 I972 SHEET 2 BF 4 HEAT EXCHANGE STRUCTURE FOR A HOT AIR HEATERBACKGROUND OF THE INVENTION This invention relates generally to hot-airfurnace heaters, and particularly to a novel heat exchange structuretherefor, prior to venting the combustion products to the exterior.

Hot-air furnaces are used widely in modern homes. Conventionally, suchfurnaces include a burner gun assembly firing into a combustionchamberwhich is joined to some form of radiating means for heating air andwhich serves as a flue for the discharge of the products of combustion.The radiating means provides a circuitous flow of the hot products ofcombustion so that a two-stage heat exchanger is suited ideally forheating the air. The air to be heated is provided to a distributionconduit which is spaced around the combustion chamber and radiatingmeans, and adjacent thelatter, forms a plenum or distributing space forthe ducts leading the heated air to the desired points of reception.Improvements in hot air furnace construction generally are directed toan increase in the efficiency of combustion and/or heat transfer formore even heat distribution and to lower the temperature of thedischarged products of combustion.

SUMMARY OF THE INVENTION The invention in general providesfor a moreeffective heat transfer structure whereby the hot products of combustionare distributed more evenly over the extent of the radiating means orheat exchange surfaces by means of flow dividers therein, which areparallel to the normal gas flow, so that the complexity of the gas flowis minimized. Thus, the pressure loss in the flow passages is notincreased materially. Concomitant with the use of the flow dividers isthe use of a novel cross-over port structure to aid in the distributionof the products of combustion in the radiating means.

Further, the exterior wall structural member or outside panel of thesecond stage of the heat exchange surfaces opposite the cross-over portstructure between the primary and secondary stages of the heat exchangeris provided with concentric corrugations to overcome the unequal heatingand expansion of the panel in this area.

Accordingly, it is an overall object of this invention to provide formore effective heat transfer in a hot-air furnace.

Another object is to provide for a more efficient heat exchangerconstruction.

These and other objects, advantages and features of the invention willbecome more apparent from the following description taken in conjunctionwith, the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is an exposed side view of thefurnace assembly with the heat exchanger shown in full outline;

FIG. 2 is an isometric view, partly in section, showing the novelconstruction of the heat exchanger;

FIG. 3 is a view, partly in section, of the outside panel of the heatexchanger opposite the cross-over port structure;

FIG. 4 is a cross section taken along lines 4-4 of FIG. 3 showing theflow of the flue gases or products of combustion;

FIG.5 is a view showing a support channel between the two stages of theheat exchanger taken along line 5-5 of FIG. 4;

FIG. 6 is a view, partly in section, of the clean-out hole panel of theheat exchanger;

FIG. 7 is a partial section view taken along line 7-7 of FIG. 6 showingthe cross-over port structure; and

FIG. 8 is a partial cross section of the corrugated panel of the heatexchanger taken along line 8-8 of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to FIG. 1 of thedrawings, a hot-air furnace cabinet assembly is disclosed at 1,comprising the air intake section 2 with the air blower assembly 3, anda control assembly at 4, positioned therein. The air distributingconduit 5 leads from the air intake section 2 and surrounds thecombustion chamber 6 and the radiating means or heat exchangeconstruction 10, the latter being a two-stage heat exchanger which isjoined to the combustion chamber by V-band clamp means 9.

A burner gun assembly 7 fires into the combustion chamber 6 and supportsthe fuel pump assembly and combustion air blower 8 thereon.

The heat exchanger '10 comprises the first stage 11 having thetransition portion lla where the bottom cylindrical structure, which isconnected to the circular combustion chamber 6, is changed to arectangular structure having a closed top 11b; and the second stage ofthe exchanger is shown at 12.

Referring specifically to FIG. 2, partially in section, the two stagesof a heat exchanger are shown disclosing the manner in which thecross-over port structure and the support flanges hold the two stagestogether. The cross-over port structure at 13 is a substantiallyrectangular vertical inlet into the second stage for the products ofcombustion leaving the first stage and is flared outwardly to join theinside wall of the second stage, as disclosed best in FIG. 7. The outletfrom the second stage is disclosed as circular at 14 leading to flue 15(see FIG. 1). This outlet connection and flanges on the opposite paneljoined to the cabinet wall (not shown) support the heat exchanger in thecabinet. An inspection door and control air bleed is at 16, shown morecompletely in FIG. 1, and clean-out ports are disclosed at 17, thecovers therefor having been omitted for clarity in FIG. 2, but are shownfiguratively at 17a in FIG. 6.

The directing flanges 18 are generally parallel to the flow of theproducts of combustion from the inlet 13 to the outlet 14, these flangesbeing spaced to provide equal or proportional volumes in the secondstage as desired and having bent directional portions at 180 adjacentinlet 13 for directing the flow in a controlled manner around the secondstage, and are also bent adjacent outlet 14 at 18b. In addition to theflared cross-over port structure at 13, support flanges at 19, one onlybeing shown atthecut-away section, and in cross section in FIG. 5, areused to hold the two stages together. Centrally located, heat expansioncorrugations in the panel opposite the cross-over port structure areshown at 20 (also see FIG. 8), these being concentric and havingdimensions such that the outer corrugation has a diameter larger thanthe length of the cross-over port structure or inlet 13, as shown inFIG. 3, to

' compensate for any unequal heat distribution patterns resulting fromthe flow out of the cross-over port structure.

FIGS. 3 and 4 disclose the interior spacing or inside passage 21 betweenthe first and second stages of the heat exchanger. The proportions ofthis spacing between these stages and that between the exchanger and thecabinet wherein the pumped air is exposed to the heat of the combustiongases in the furnace can be determined by experiment, and likewise theextent of the surface areas of the heat exchanger, the passages andsurfaces being chosen in accordance with heating requirements.

In FIG. 4, the full .arrows disclose the passage of the products ofcombustion upward from the combustion chamber into the first stage, theflow of somebeing reversed by the top 11b ofthe first stage to join theoutward flow along with the other products of combustion into thecross-over port structure at 13, and the dashed arrows show the flowbetween the directing flanges in the second stage toward the outlet 14.

Thus, there has been shown and described how an improved heat exchangestructure can be used in a heater to more evenly distribute hot productsof combustion to result in an overall increase in heat exchangeefficiency to provide for better heating of air and a lowering of fluegas temperatures.

Other modifications and variations of the invention as hereinbefore setforth may be made without departing from the spirit and scope thereof,and therefore only such limitations should be imposed as are indicatedin the'appended claims.

Iclairn:

l. in the combination defining a heater construction for providingheated air and including combustion means, a heat exchanger structurecomprising wall members defining a pair of concentrically spaced,interconnected heat exchange chambers, the first or inner of saidchambers being connected to the combustion chamber of said combustionmeans and receiving hot products of combustion directly therefrom, thesecond or outer of said chambers being joined to the first heat exchangechamber by a cross-over port structure defining an inlet thereinto forreceiving said products of combustion from said inner of said chambers,and an outlet located in the exterior wall of said outer of saidchambers opposite the exterior wall thereof adjacent said inlet for thedischarge of said products of combustion from the second heat exchangechamber, said cross-over port structure being substantially rectangularin configuration and extending vertically at the junction between saidchambers whereby the flow of said products of combustion into saidsecond heat exchange chamber is more widely distributed adjacent saidinlet and itself provides additional heat exchange surface.

2, In the combination as defined in claim 1, said second chamber havinga plurality of flow divider flange strips extending from adjacent saidinlet to adjacent said outlet for controlled guidance of the flow ofsaid products of combustion therebetween.

3. In the combination as defined in claim 2, said flange strips beingsubstantially parallel to the normal flow of said products of combustionin said second chamber to minimize the complexity of said flow thereinand to keep the pressure loss at a minimum.

4. In the combination as defined in claim 3, the wall member definingthe exterior wall of said second heat exchange chamber adjacent saidcross-over port structure having a corrugated surface to compensate forunequal heat transfer thereto, said port structure being flaredoutwardly from said first chamber to its junction with said secondchamber.

5. In the combination as defined in claim 4, said surface having a pairof concentric corrugations centered on said wall member, the outercorrugation thereon having a diameter greater than the length of saidport structure.

6. In the combination as defined in claim 3, the spacing between saidchambers of said heat exchanger structure and the surface areas of saidchambers being determined by air heating requirements.

1. In the combination defining a heater construction for providingheated air and including combustion means, a heat exchanger structurecomprising wall members defining a pair of concentrically spaced,interconnected heat exchange chambers, the first or inner of saidchambers being connected to the combustion chamber of said combustionmeans and receiving hot products of combustion directly therefrom, thesecond or outer of said chambers being joined to the first heat exchangechamber by a cross-over port structure defining an inlet thereinto forreceiving said products of combustion from said inner of said chambers,and an outlet located in the exterior wall of said outer of saidchambers opposite the exterior wall thereof adjacent said inlet for thedischarge of said products of combustion from the second heat exchangechamber, said cross-over port structure being substantially rectangularin configuration and extending vertically at the junction between saidchambers whereby the flow of said products of combustion into saidsecond heat exchange chamber is more widely distributed adjacent saidinlet and itself provides additional heat exchange surface.
 2. In thecombination as defined in claim 1, said second chamber having aplurality of flow divider flange strips extending from adjacent saidinlet to adjacent said outlet for controlled guidance of the flow ofsaid products of combustion therebetween.
 3. In the combination asdefined in claim 2, said flange strips being substantially parallel tothe normal flow of said products of combustion in said second chamber tominimize the complexity of said flow therein and to keep the pressureloss at a minimum.
 4. In the combination as defined in claim 3, the wallmember defining the exterior wall of said second heat exchange chamberadjacent said cross-over port structure having a corrugated surface tocompensate for unequal heat transfer thereto, said port structure beingflared outwardly from said first chamber to its junction with saidsecond chamber.
 5. In the combination as defined in claim 4, saidsurface having a pair of concentric corrugations centered on said wallmember, the outer corrugation thereon having a diameter greater than thelength of said port structure.
 6. In the combination as defined in claim3, the spacing between said chambers of said heat exchanger structureand the surface areas of said chambers being determined by air heatingrequirements.